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Farf Samba Member
Joined: July 12, 2009 Posts: 463 Location: Colorado
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Posted: Fri Jun 17, 2016 12:21 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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Unfortunitly, yes...Since you know your motors are ok and you have the fan switch accessed you can use an ohm meter and check for continuity to ground at speed 1 wire to ground and speed 2 wire to gtound other than the wire connections the only thing from the switch through the motor and to ground are the resistors. Look at current track roughly 7.5 and 8, speed 2 and 1 respectively at the fan speed switch and follow the path downward through the motors to ground. Disconnect each wire at the switch and put one meter probe on it and the other probe to a good ground if the current path isn't broken you should read continuity on your meter. If not, bad connections or resistors, you will probably have to dig in to find the exact problem. |
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Syncro Jael Samba Member
Joined: December 19, 2013 Posts: 2204 Location: Utah
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Posted: Fri Jun 17, 2016 12:37 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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Farf wrote: |
Unfortunitly, yes...Since you know your motors are ok and you have the fan switch accessed you can use an ohm meter and check for continuity to ground at speed 1 wire to ground and speed 2 wire to gtound other than the wire connections the only thing from the switch through the motor and to ground are the resistors. Look at current track roughly 7.5 and 8, speed 2 and 1 respectively at the fan speed switch and follow the path downward through the motors to ground. Disconnect each wire at the switch and put one meter probe on it and the other probe to a good ground if the current path isn't broken you should read continuity on your meter. If not, bad connections or resistors, you will probably have to dig in to find the exact problem. |
So if I unplug the "fan speed selector switch" and hook an ohm meter ground to black and red on speed "one" (BK/W) wire. I should have continuity? Same on speed "two"? (BK/G) wire? Am I just looking for a connection or looking for resistance? If I don't have continuity then the resistor(s) are bad or I have a break in the wire? Sorry, I am learning.
It is interesting that also speed "three" has stopped working. Does it also tracks through the resistor pack or through the A/C relay?
There is no easy way to get to the resistors? What are the odds both will go bad at once, or does only one have to go bad to effect everything? Any way to wire in resistors without removing the whole damn thing again?
Also could a faulty resistor be my issue with the wiring at the A/C relay getting hot? _________________ 1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat) |
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Farf Samba Member
Joined: July 12, 2009 Posts: 463 Location: Colorado
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Posted: Fri Jun 17, 2016 1:11 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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Yes, you are correct on your ohm meter test points. It looks like if uou lost one resitor in the bank than both motors would try to run on one resistor, maybe self-imploding. Its possible that your hot relay could be from something in the resistor bank, but I don't know for sure. |
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Syncro Jael Samba Member
Joined: December 19, 2013 Posts: 2204 Location: Utah
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Posted: Fri Jun 17, 2016 1:33 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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Farf wrote: |
Yes, you are correct on your ohm meter test points. It looks like if uou lost one resitor in the bank than both motors would try to run on one resistor, maybe self-imploding. Its possible that your hot relay could be from something in the resistor bank, but I don't know for sure. |
I will do the tests. If it looks like the cabinet comes down again, , then I am really thinking of wiring the resistors where they are accessible next to the expansion valve. So if it ever happens again...
Again thanks for your response. _________________ 1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat) |
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Syncro Jael Samba Member
Joined: December 19, 2013 Posts: 2204 Location: Utah
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Posted: Fri Jun 17, 2016 2:37 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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Farf wrote: |
Yes, you are correct on your ohm meter test points. It looks like if uou lost one resitor in the bank than both motors would try to run on one resistor, maybe self-imploding. Its possible that your hot relay could be from something in the resistor bank, but I don't know for sure. |
Farf,
I tested all the wires from the speed selector switch in the dash. Continuity on the WH, WH/BL, Y, but not the GR/BL.
So does this mean I have a resistor gone?
I went down to the storage unit that has our family stash of vanagon parts and pulled this out of parts from an 87 Syncro tin top. I have my resistor packs, good fans, and a nice evaporator. You never know when you will need stuff so we let nothing go. I am planning to mount these resistors in the cabinet behind the speakers where they are accessible to change/diagnose. There should be plenty of cool air movement for them. If someone see's a problem or why I shouldn't let me know. It should be painless to wire these into the existing harness and keep things nice and tidy.
_________________ 1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat)
Last edited by Syncro Jael on Fri Jun 17, 2016 4:02 pm; edited 1 time in total |
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Howesight Samba Member
Joined: July 02, 2008 Posts: 3274 Location: Vancouver, B.C.
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Posted: Fri Jun 17, 2016 4:00 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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The highest speed (4) is switched by a separate relay connected directly to the 50 amp fusible link with no resistor. Look at the wiring diagram on page 2 of this thread. The two resistors consist of stacked resistors that reduce current and voltage the most when current must pass through all three stacked parts of the resistor. Setting the fan switch to "speed 1" forces current to go through all three parts of the resistor and so on. Speed 3 powers a relay inside the AC relay which then connects to terminal 3 in both the series resistors. Speed 4 powers the "evap. fan relay" in the wiring diagram. Speeds 1 and 2 carry the most current through the fan switch because they carry the fan current, not just the signal to the relays, which is what happens for speeds 3 and 4.
In doing my Front AC install, I noted that the pigtail socket at the fan switch can get dodgy, but I was working with a salvaged pigtail.
It looks to me as though there has been a failure in the "evap. series resistor" between points 3 and 4. It is possible that one or both wires have disconnected from their terminals at the resistor. More likely, however, the resistor(s) has failed. I don't recall from your thread whether you were able to service those fans when you refurbished your AC system, but they can draw a lot of power when the bearings are dry.
It might be possible to lower the evaporator enough to reach inside and replace the resistors, without disconnecting the refrigerant lines.
From Dave Vickery's pics, it looks like you might be able to remove a fan from the front of the evaporator cabinet and then gain access to the resistors. Notice how Dave notched his cabinet to allow it to be dropped with the evaporator core still connected?) :
Or maybe access the resistors from the speaker holes through an access hole you cut:
_________________ '86 Syncro Westy SVX |
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Syncro Jael Samba Member
Joined: December 19, 2013 Posts: 2204 Location: Utah
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Posted: Fri Jun 17, 2016 4:19 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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Howesight wrote: |
The highest speed (4) is switched by a separate relay connected directly to the 50 amp fusible link with no resistor. Look at the wiring diagram on page 2 of this thread. The two resistors consist of stacked resistors that reduce current and voltage the most when current must pass through all three stacked parts of the resistor. Setting the fan switch to "speed 1" forces current to go through all three parts of the resistor and so on. Speed 3 powers a relay inside the AC relay which then connects to terminal 3 in both the series resistors. Speed 4 powers the "evap. fan relay" in the wiring diagram. Speeds 1 and 2 carry the most current through the fan switch because they carry the fan current, not just the signal to the relays, which is what happens for speeds 3 and 4.
In doing my Front AC install, I noted that the pigtail socket at the fan switch can get dodgy, but I was working with a salvaged pigtail.
It looks to me as though there has been a failure in the "evap. series resistor" between points 3 and 4. It is possible that one or both wires have disconnected from their terminals at the resistor. More likely, however, the resistor(s) has failed. I don't recall from your thread whether you were able to service those fans when you refurbished your AC system, but they can draw a lot of power when the bearings are dry.
It might be possible to lower the evaporator enough to reach inside and replace the resistors, without disconnecting the refrigerant lines.
From Dave Vickery's pics, it looks like you might be able to remove a fan from the front of the evaporator cabinet and then gain access to the resistors. Notice how Dave notched his cabinet to allow it to be dropped with the evaporator core still connected?) :
Or maybe access the resistors from the speaker holes through an access hole you cut:
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I am planning to install these resistors inside the evaporator cabinet. From playing with the expansion valve jacket, while the system was running, there is plenty of cold air movement inside.
I just checked the resistors that I had in storage and they both have the same readings: Wire BL to WH (006) BL to GR/BL (014) BL to WH/BL (034). So they check out as good.
Again if anyone can see a reason not to install these where they are accessible without taking down the evaporator cabinet, CHIME IN. Yes, Dave did a good job modifying the cabinet. I also modified the drivers side of mine so I can get the expansion valve out easily. I cut some wrenches down short and the last time I swapped expansion valves it took about 20 minutes total.
I was also thinking about my ohm test from the fan speed selector switch. When opening up the old harness I noticed the crimp connections that the factory used to connect the GR/BL and WH/BL wires from the resistor packs together. It is possible that when I was working in the evaporator cabinet that harness could have been stretched and severed the connection.
If only one resistor had gone bad, I should have still had a connection through the other one since they are spliced together mid harness. It's possible? And again, if speed setting #3 is on the other circuit why is it not working? Can somebody answer that one? Thanks _________________ 1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat) |
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Farf Samba Member
Joined: July 12, 2009 Posts: 463 Location: Colorado
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Posted: Fri Jun 17, 2016 5:31 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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Speed 3 still needs to go through the resistor banks. I'm thinking that Howesight's take on the problem being between points 3 and 4 on the resistor bank is spot on and a great place to start. I think as long as the resistors are in the airstream you should be ok, someone else may chime in on this. |
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Syncro Jael Samba Member
Joined: December 19, 2013 Posts: 2204 Location: Utah
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Posted: Fri Jun 17, 2016 7:21 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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bobbyblack wrote: |
This topic reminds me that the AC in my '87 doesn't function at all. I looked under the dash, pulled every fuse and checked each with continuity tester when I got the rig in October. They are all fine. I am not yet to the part where I get any action at all with any controls, so I have just the very start of all this other stuff up to this point in the thread.
Where to start looking? I do have refrigerant in the system, but not sure how much pressure (don't need to ask how I know) Would low pressure cause the entire system to not work, or do things like fan, compressor, etc try to start with low pressure anyway?
Thanks |
Just to answer your question. Yes the fans should work without refrigerant in the system. The compressor will not engage until there is enough pressure/refrigerant. But everything else should function. I would start out evacuating the system, check for leaks, then give it a charge and see what happens. You won't be out much.
Farf, thanks so much for your help. I have been replacing some other wiring and cleaning up connections. So far it has helped with some of the hot wiring, but it is still warm. I am sure those fans up top are pulling some amps. My black and white wires headed up there get toasty warm. _________________ 1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat) |
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Syncro Jael Samba Member
Joined: December 19, 2013 Posts: 2204 Location: Utah
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Posted: Sat Jun 18, 2016 4:09 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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Just to bring this repair to an end.
I guess during all the work on the A/C system and having the cabinet down a couple of times, one of the plastic mounts for one resistor must have broken and was lying sideways on the cabinet bottom. Those things must get extremely hot because it burned a black hole in the wood. It wore through the coating, on the resistor, and I am sure overheat and rubbing on the cabinet made it fail.
The other resistor was still in its mount, but tested bad. So what are the odds that both will fail at the same time? Pretty good odds in my case.
I was thinking of mounting the resistor packs where they would be more accessible, but after seeing how hot it must get I am sure there is a reason the engineers mounted them in the cold air stream of the A/C evaporator cabinet. So I made some new "metal" mounts, insulated the bases, and installed them in the factory locations.
A quick test once all the soldered, heat shrink, connections were made and the van is back to normal.
I now have a set of new relays for the system that are not needed.
So if your A/C evaporator fans will only run on HIGH speed number (4)four only. And you have checked all the appropriate fuses. It will be your resistors that have failed. You can check the continuity of #1 and #2 speeds at the speed switch on the dash. If you do not have continuity, then the resistors have failed for sure.
Thanks to many of you who guided me through this repair.
NOW I HAVE TO GO REINSTALL THE CABINETRY and ROOF PLENUM... But it gave me a chance to re-oil the fan motor bearings again.
Cheers ! _________________ 1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat) |
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blurat Samba Member
Joined: July 18, 2012 Posts: 50 Location: Central Ca
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Posted: Sat Mar 18, 2017 3:19 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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FYI only. Measured my temp at the fuse with air on High192-209
Installed a length of 12 gauge wire from B+ alt to the load side of the fuse and rechecked, 160-172.
ran for 45 minutes and no problems noted.
This was all after I melted the fuse and block and installed Van Cafe replacement.............while eating an awesome cookie.
Thanks farf for the diagram |
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termuehlen Samba Member
Joined: May 02, 2012 Posts: 994 Location: Redwood City
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Posted: Fri Mar 31, 2017 11:37 am Post subject: Re: 87 Vanagon A/C Electrical Problem |
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This is a great thread. Very helpful! I took a look at my '88 Westy A/C wiring and guess what I found:
This seems like a pretty common problem and it makes me wonder how many times this has resulted in an electrical fire. For anyone who has an operating A/C system, this should be tops on their list of things to inspect. It must also get pretty hot back inside this area because the plastic part of my 20Amp fan fuses were also in pretty bad shape:
Here's what things look like following my repair. Now it is time to operate it and see how this goes. I may still add another conductor if I feel this isn't quite enough.
_________________ 1988 Westfalia automatic Subaru OBD1
1986 syncro tintop wbx |
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Paulbeard Samba Member
Joined: July 10, 2015 Posts: 2604 Location: Seattle
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Posted: Sat Apr 01, 2017 7:22 am Post subject: Re: 87 Vanagon A/C Electrical Problem |
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termuehlen wrote: |
This is a great thread. Very helpful! I took a look at my '88 Westy A/C wiring and guess what I found:
This seems like a pretty common problem and it makes me wonder how many times this has resulted in an electrical fire. |
More fuel ( ) for the theory that electrical fires in these old rigs are at least as big a risk as aging fuel lines? _________________ Currently -> Frida: 87 Tizian Red (mostly) Vanagon GL Westfalia w/ 2.0L ABA conversion
Formerly -> Steward of a 73 Super Beetle (Beater) and 67 Beetle 1300 (Little Max) both names by POs
— dhaavers |
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Rick Bowman Samba Member
Joined: July 03, 2014 Posts: 4 Location: VIRGINIA
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Posted: Wed Jun 20, 2018 6:25 am Post subject: Re: 90 Vanagon A/C Electrical Problem |
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Both S51 fuses are blowing when A/C is turned on. Besides fan motors, what else can cause this? (Just hoping it's not the fans) |
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Steve Arndt Samba Member
Joined: August 01, 2005 Posts: 1780 Location: Boise, Idaho
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Posted: Mon Jun 10, 2019 12:38 pm Post subject: Re: 87 Vanagon A/C Electrical Problem |
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Bump. My evap fan quit working today at all settings. Worked perfect before today.
Background I have already replaced the 50A foil fuse with a 50 amp breaker and upgraded the supply wiring to 8 gauge 15 years ago. I haven't taken the panel down. Where should I look first? System was operating perfectly. Went into a store and restarted the system was running on restart minus the evap blower. _________________ Steve
Steve's 87 Syncro project |
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Steve Arndt Samba Member
Joined: August 01, 2005 Posts: 1780 Location: Boise, Idaho
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Posted: Tue Jun 11, 2019 7:56 am Post subject: Re: 87 Vanagon A/C Electrical Problem |
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Steve Arndt wrote: |
Bump. My evap fan quit working today at all settings. Worked perfect before today.
Background I have already replaced the 50A foil fuse with a 50 amp breaker and upgraded the supply wiring to 8 gauge 15 years ago. I haven't taken the panel down. Where should I look first? System was operating perfectly. Went into a store and restarted the system was running on restart minus the evap blower. |
Found one of the 20A blower motor fuses blown. The original VW fuses are a PITA to remove they always fall apart in the fuse holder. Replaced and cleaned things up and its good to go for now. I know my blower motors are probably drawing extra current. I'm going to address that when I drop (or it falls down again) the evaporator. _________________ Steve
Steve's 87 Syncro project |
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